This invention relates generally to imaging apparatuses and digital cameras and, more particularly, to an imaging apparatus for reading charges out of light receiving elements of a CCD imager to create a low-resolution camera signal, and to a digital camera provided with such an imaging apparatus. Description of the related art.
In a conventional digital camera in which, where charges are read with thinning out from a CCD imager, the read-out charges are transferred to the CCD imager and then outputted therefrom in a separate fashion.
However, such charge reading with thinning out is equivalent to charge sampling. According to a sampling theorem, such an output camera signal contains aliasing components. A filter can eliminate such aliasing components. The addition of a filter, however, raises cost correspondingly.
It is therefore a primary object of the present invention is to provide, at low cost, an imaging apparatus in which noise is prevented from occurring.
Another object of the invention is to provide at low cost a digital camera in which noise is prevented from occurring.
An imaging apparatus of the present invention comprises: a CCD imager of an interline transfer scheme having a plurality of light receiving elements and a plurality of vertical transfer registers; a color filter having a plurality of color elements arranged such that one of the color components corresponds to one of the light receiving elements; and a pulse generator for generating a drive pulse to drive the CCD imager; wherein the color filter has a vertical column arranged with a plurality of colors of color elements, and the drive pulse is a pulse to drive the CCD imager such that charges of a same color of color elements are mixed together on a corresponding vertical transfer register to the vertical column.
According to this invention, the CCD imager of an interline transfer scheme has a plurality of light receiving elements and a plurality of vertical transfer registers while a color filter has a plurality of color elements, each of which corresponds to associated one of the light receiving elements. The CCD imager is driven by a drive pulse generated by a pulse generator. Here, the color filter has a vertical column arranged with a plurality of color elements. Also, the drive pulse is a pulse to drive the CCD imager such that the charges of a same color of the color components are mixed together on a corresponding one of the vertical transfer registers to the vertical column.
The drive to the CCD imager such that the charges of a same color of the color elements are mixed together provides a filtering process to be performed within the CCD imager, thereby removing aliasing components. Accordingly, there is no necessity of newly providing a filter circuit to remove noise.
In one embodiment of the invention, the drive pulse includes a first read pulse to read a first charge produced by a first light receiving element onto the corresponding vertical transfer register, a vertical transfer pulse to transfer the first charge in a vertical direction, and a second read pulse to read a second charge produced by a second light receiving element onto the vertical transfer register when the first charge has been transferred in the vertical direction by a predetermined distance. Here, the first light receiving element and the second light receiving element have a same color of color elements.
Preferably, the vertical column is arranged alternately with two color of colors elements, and the predetermined distance corresponding to a length of two light receiving elements in the vertical direction.
In another embodiment of the invention, the color filter is a filter arranged with primary colors of color elements in a Bayer arrangement.
In still another embodiment of the invention, the vertical transfer register is formed by a plurality of metals, and at least three of the metals is assigned to one of the light receiving elements.
A digital camera according to the present invention comprises a CCD imager of an interline transfer scheme having a plurality of light receiving elements and a plurality of vertical transfer registers; a color filter having a plurality of color elements arranged such that one of the color components corresponds to one of the light receiving elements; and a driver for driving the CCD imager; wherein the color filter has a vertical column arranged with a plurality of colors of color elements, and the drive means driving the CCD imager such that charges of a same color of color elements are mixed together on a corresponding vertical transfer register to the vertical column.
According to this invention, the CCD imager of an interline transfer scheme has a plurality of light receiving elements and a plurality of vertical transfer registers while a color filter has a plurality of color element each of which correspond to associated one of the light receiving elements. The CCD imager is driven by a drive means. Here, the color filter has a vertical column arranged with a plurality of color elements. Also, the driver drives the CCD imager such that the charges of a same color of the color components are mixed together on a corresponding one of the vertical transfer registers to the vertical column.
The drive to the CCD imager such that the charges of a same color of the color elements are mixed together provides a filtering process to be performed within the CCD imager, thereby removing aliasing components. Accordingly, there is no necessity of newly providing a filter circuit to remove noise.
In one embodiment of the invention, the drive means includes a first read means to read a first charge produced by a first light receiving element onto the vertical transfer register, a vertical transfer means to transfer the first charge in a vertical direction, and a second read means to read a second charge produced by a second light receiving element onto the vertical transfer register when the first charge has been transferred in the vertical direction by a predetermined distance. Here, the first light receiving element and the second light receiving element have a same color of color elements.
Preferably, the vertical column is arranged alternately with two colors of color elements, and the predetermined distance corresponding to a length of two light receiving elements in the vertical direction.
In another embodiment of the invention, the color filter is a filter arranged with primary colors of color elements in a Bayer arrangement.
In still another embodiment of the invention, the vertical transfer register is formed by a plurality of metals, and at least three of the metals being assigned to one of the light receiving elements.
In yet another embodiment of the invention, an exposure means exposes a subject image to the CCD imager. Here, a calculation means calculates an optimal amount of exposure by the CCD imager. A setting means sets the optimal amount of exposure to the exposure means. A disabling means disables the second read means depending upon the optimal amount of exposure.
Preferably, the optimal amount of exposure is defined based on a shutter speed, and the disabling means disabling the second read means when the shutter speed is higher than a predetermined value.